In general, a silver halide color photographic material (hereinafter simply referred to as a "photographic material") is produced by coating at least one light-sensitive silver halide emulsion layer on a plastic film support. As the plastic film support, generally employed are a cellulosic polymer such as typically tri(acetyl cellulose) (hereinafter referred to as "TAC") and a polyester polymer such as typically poly(ethylene terephthalate) (hereinafter referred to as "PET") . These are described in, for example, Research Disclosure No. 307,105 (November, 1989), Item XVII.
A photographic material having the plastic film support is generally grouped into two groups; one being in the form of a sheet film such as a cut film, and the other being in the form of a roll film such as typically a picture-taking film having a width of 35 m/m or so. The latter is generally housed in a patrone and is charged in a camera for picture-taking.
As a support for a roll film, TAC is predominantly used. The most characteristic feature of this is that TAC has no optical anisotropy and has a high transparency. Another excellent characteristic of this is that TAC has an excellent property of easily smoothing the curl of a developed photographic material having it as a support. Specifically, since a TAC film has a relatively high water-absorbing property, though being a plastic film, because of its characteristic molecular structure, the molecular chain of the film comes to be fluid after the support film of TAC has absorbed water during development of a curled roll film so that the molecular chain as fixed in the curled roll film is to be rearranged. As a result, TAC displays an excellent property of easily smoothing the curl of the roll film having it as a support.
However, a photographic material having a support not having such an easily curl-smoothing property unlike TAC involves various problems, if used in the form of a roll film. For example, during its development, the photographic material is often "developed unevenly" or "scratched" or "bent". In addition, in the printing step where the developed film is printed in printing papers, the film is often scratched or causes out-of-focusing or is jammed during its feeding.
On the other hand, since TAC have a relatively large water absorption, it is gradually decomposed when stored for a long period of time to release an acid (acetic acid) therefrom. Cyan, magenta and yellow dye-forming couplers to be used in photographic materials and the dyes to be derived from such couplers are affected by the released acid, whereby the coloring capacity of the couplers is lowered and the formed dyes are faded. Above all, yellow dye-forming couplers and the dyes derived from them are affected more by the acid than other cyan and magenta dye-forming couplers and the dyes derived from them. Of yellow dye-forming couplers, the couplers to be used in the present invention have a higher coupling activity than conventional pivaloylacetanilide-type couplers, and the dyes derived from the former have a larger molecular extinction coefficient than those derived from the latter. The couplers to be used in the present invention are comparable to benzoylacetanilide-type couplers with respect to their coloring properties. Regarding the color image fastness, the couplers to be used in the present invention are almost similar to pivaloylacetanilide-type couplers. Regarding the spectral absorption characteristics of the dyes to be derived from the couplers to be used in the present invention, their absorption of green light in a longer wavelength range is small and the couplers have excellent color reproducibility. Therefore, if the couplers having such excellent coloring properties, color image fastness and color reproducibility may be incorporated into photographic materials having the TAC support, without lowering the storage stability of themselves and also the storage stability of the color images derived from them, these excellent characteristics of the couplers may further be improved and, additionally, the yellow dye-forming couplers themselves may be improved greatly. Given these situation, it has heretofore been desired to attain the technical means capable of satisfying the request.
The use of photographic materials has been diversified widely in these days, and the technologies for rapid feeding of a photographic film in a camera during picture-taking with it, elevation of the image magnification and reduction of the size of camera have advanced noticeably. Under the advanced technologies, the supports of photographic materials are needed to have high strength and high dimension stability and to be thin as much as possible. In addition, with much reduction of the size of camera, the demand for reducing the size of patrone has also become great.
Reduction of the size of a patrone involves two problems.
The first problem is that the reduction of the thickness of the roll film to be in the patrone is often accompanied by lowering of the mechanical strength of the film itself. In particular, the bending elasticity of a roll film decreases in proportion to the third power of the thickness thereof. Photographic materials generally have gelatin coated on the support, and the gelatin layer is shrunk under a low humidity condition to be curled in the widthwise direction to a gutter-like (U-shaped) form. The support is therefore needed to have a bending elasticity to be resistant to the shrinking stress.
The second problem is that the roll film in a small-sized patrone with a small-sized spool is strongly curled during storage of the film. In the conventional 135 system device, the smallest diameter of a roll film of 36 exposures as housed in the patrone is 14 mm. If the patrone is desired to be more small-sized so that the diameter may be 12 mm or less or further 9 mm or less, the hardly smoothable curl of the roll film as housed in the patrone would be much greater to cause various troubles in handling the exposed film. For instance, if the exposed film taken out from such a small-sized patrone is developed in a mini-laboratory automatic developing machine, the film would be curled up during handling it since only one edge of the film is fixed to the leader but the other one is not, so that feeding of a processing solution to the curled-up area would be delayed to cause so-called "uneven development". In addition, the curled-up film would be crushed by the rollers in the machine and the film being processed would then be "bent or scratched".
When an long-size unexposed film (for 36 exposures) that has been drawn out from its patrone is charged into a supply room by winding it into a roll form (this operation is referred to as "core-setting"), the number of winding times thereof is larger than that of films for 12 exposures or 24 exposures so that it is wound tightly (namely, it is wound so tightly that the wound roll is hardly loosened). In addition, in this case, the diameter of the wound innermost layer of the roll film in the supply room is naturally small. Therefore, the leading side (tongue) of the long-size film is tightly curled when rolled into a roll film. For these reasons, the exposed film that is cased in the patrone is still tightly curled and the tightly-curled tongue of the roll film is to firmly adhere to the inner wall of the patrone. As a result, it is extremely difficult to take out the tongue of the exposed film with a drawing tool before its development.
In order to attain the above-mentioned two themes in a roll film, one being the strong mechanical strength and the other being the easily-smoothable property, there are two methods. The first method is to modify a TAC support having an easily-smoothable property to thereby enhance the mechanical strength thereof. The second method is to improve a polyester support having a high mechanical strength, such as typically a poly(ethylene terephthalate) (PET) support to be employed in the present invention, in order that it hardly has the habit of curling.
The achievement of the themes in question by the former method is extremely difficult. This is because the thickness of the TAC support in the current photographic materials is 122 .mu.m, and if the thickness of the support is reduced to 100 .mu.m, because the modulus of bending elasticity is generally proportional to the third power of the thickness, the modulus of bending elasticity of the 100 .mu.m-thick support becomes about 50% that of the 122 .mu.m-thick support. For this reason, the support must be modified in such a manner that the modified 100 .mu.m-thick support has the modulus of elasticity of about two times as large as the non-modified 100 .mu.m-thick one in order to attain the purpose. On the other hand, if the spool diameter is reduced to 10 mm or less, even the uncurlable TAC could not sufficiently uncurl during development with the result that the still curled photographic material is to involve the above-mentioned "uneven development" and "bending or scratching" troubles. In addition, the operation of drawing the tongue of the roll film out of the patrone is difficult. It is therefore considered extremely difficult to satisfy the three themes of the "two times elevation of the modulus of elasticity", the "improvement of the uncurling property" and the "improvement of the easy drawability of the tongue of the roll film from its patrone".
On the other hand, where the achievement of the themes is attained by the latter method of, for example, employing PET, a 100 .mu.m-thick PET support or even a 90 .mu.m-thick PET support may have the same bending elasticity as a 122 .mu.m-thick TAC support because PET naturally has a high modulus of elasticity. In addition, from the present inventor's investigations, it has been clarified that the use of polyester supports such as PET is preferred to the use of the above-mentioned TAC supports, since the former is almost free from the deterioration of photographic materials during their storage and the deterioration of the color images formed though the latter is not free.
It has heretofore been considered that polyester supports which are inexpensive and are suitable for mass-production and which have high mechanical strength and dimension stability, such as typically PET, may be substitutable for TAC in order to attain the above-mentioned objects. However, when photographic materials having such polyester supports are used as roll films which are popular in this technical field, they are strongly curled and the curled films are hardly uncurled or smoothed. Accordingly, the handlability of the developed films is bad. For these reasons, the use of polyester supports in photographic materials has heretofore been limited, though they have the above-mentioned excellent properties.